1. Field of the Invention
The invention relates to the field of air conditioning, heating, ventilating, and similar systems in which sheet metal duct work is used for conveying an air supply within buildings, residences, and the like. Particularly, the invention provides a connecting device for joining a section of sheet metal duct work to a wall or second duct having an opening to receive the first duct segment.
2. Disclosure Statement
In U.S. Pat. No. 2,963,783, issued Dec. 13, 1960, to J. P. Field, sheet metal fittings are disclosed in which a roll of deformable tabs forms a skirt which projects into an opening of a wall, with the tabs adapted for bending into clamping engagement with the marginal portion of wall surrounding the opening. However, the tabs appear to be integral with the duct work fitting, and are not in the form of a strip for connecting a standard fitting to a hole cut to a desired size. Various connecting devices are disclosed in U.S. Pat. No. 3,988,030, issued Oct. 26, 1976, to J. L. Twedell; U.S. Pat. No. 1,935,690, issued Nov. 21, 1933, to H. J. Zack; and U.S. Pat. No. 4,009,894, issued Mar. 1, 1977, to R. L. Marquette, et al. In U.S. Pat. No. 3,727,663, issued Apr. 17, 1973, to F. J. McCabe, a device is disclosed having adapter means for mounting a fire damper in a wall.